Stripper for blow molding machine

ABSTRACT

A stripper mechanism for an automatic blow molding apparatus having a rotatable turret carrying plural sets of parison pins for forming molded articles. A set of stripper fingers project between the formed article carrying pins at an ejection station and are reciprocated parallel to the pins to strip formed articles therefrom. The span of stroke of the stripper fingers is adjustable and the fingers can be lowered to provide operation of the apparatus without an automatic stripping step. The mechanism includes a device for checking the condition of the pins after the stripping step.

United States Patent Johnson [54] STRIPPER FOR BLOW MOLDING MACHINE['72] Inventor: Joseph A. Johnson, Brigantine, NJ.

[73] Assignee: Jomar Industries, Inc., Brigantine,

[22] Filed: Aug. 24, 1970 [211 App]. No.: 66,307

[52] US. Cl. ..425/139, 425/326, 425/444, 425/387, 425/397 [51] int. Cl...r .1329! 1/14 [58] Field of Search ..l8/5 BJ, 5 BP, 5 BR, 5 EM, 18/5BP, 20 B, 2 RM, 2 RP, 30 CS, DIG. 45

[56] References Cited UNITED STATES PATENTS 3,100,913 8/1963 DeMatteo..l8/5 BJ 3,081,486 3/1963 Skvorc ..l8/2 RP 2,444,339 6/1948 Dinzl lS/DIG. 45 2,649,943 8/1953 Meyers l 8/DIG. 45 2,167,724 8/ 1939 Murphyet a]. ..l8/2 RM X 51 Oet.24,1972

2,848,770 8/1958 Schuchardt 18/2 RM X 2,923,976 2/1960 Strauss 18/2 RP X2,954,584 10/1960 Groves 1 8/2 RP X 3,570,058 3/1971 l-leinig et al...l8/5 BR Primary ExaminerJ. Spencer Overholser AssistantExaminer-Michael 0. Sutton Attorney-Stowell & Stowell ABSTRACT Astripper mechanism for an automatic blow molding apparatus having arotatable turret carrying plural sets of parison pins for forming moldedarticles. A set of stripper fingers project between the formed articlecarrying pins at an ejection station and are reciprocated parallel tothe pins to strip formed articles therefrom. The span of stroke of thestripper fingers is adjustable and the fingers can be lowered to provideoperation of the apparatus without an automatic stripping step. Themechanism includes a device for checking the condition of the pins afterthe stripping step.

8 Claims, 6 Drawing Figures PATENTED B I97? 3. 700.369

SHEET 1 BF 3 FIG. I

INVENTOR JOSEPH A. JOHNSON ATTORNEYS SHEEI 2 0F 3 PATENTED OCT 24 I972INVENTOR JOSEPH A. JOHNSON ATTORNEY) 1 STRIPPER FOR BLOW MOLDING MACHINEI BACKGROUND OF INVENTION provements in injection blow molding machinesfor automatically forming hollow articles, such as bottles, from plasticmaterials and more particularly relates to .new and novel improvementsin a stripper mechanism for multiple station injection blow moldingmachines.

2. Description of the Prior Art Injection blow molding machines thatautomatically operate to form a number of hollow articles, such asbottles, from plastic materials are fairly common in the art and inindustrial usage. A machine of the type involved is more fully describedin applicant s co-pending application Ser. No. 52,811, filed July 7,1970. Such a machine has a number of operating stations surrounding ahorizontally disposed elevatable and rotatable turret which has sidefaces carrying distinct sets of parison pins. The turret is surroundedby the angularly placed stations which include parison mold stations,blow mold stations and ejection'stations. The turret is indexed from theparison mold stations, to the blow mold stations and then to theejection stations to cause the parison pins to operatively successivelyoccupy such stations with all stations being simultaneously operative.

Each parison mold station is composed of separable mold halves with thebottom halves being fixed and the movable upper halves being carried byrams which clamp the mold halves together about the parison pins. Aninjection unit injects plastic melt into the closed parison molds aroundthe parison pins to a preset pres sure after which the parison molds areopened.

The turret is then raised to lift the pins from the bottom mold halvesand the turret is indexed to bring the parisons to the blow moldstations where the parisons are located in blow molds. With the parisonslocated in the blow molds pressurized air is passed through the parisonpins to inflate the parisons to the configuration and size determined bythe interior shape and size of the blow molds.

On completion of the blow molding, the turret is rotated in the samedirection to bring the parison pins to the ejection stations where theformed articles are 7 removed from the pins.

A problem which has been encountered with the prior art in connectionwith the ejection of the formed articles from the pins at the ejectionstation since pressurized air is used to blow the articles from thepins. This use of pressurized air tends to result in a slow ejection andalso such ejection is not fully dependable when the articles sometimesbecome stuck on the pins.

SUMMARY OF THE INVENTION The present invention provides a machine thatovercomes and eliminates the problems of known machines and thatoperates at a dependably fast production rate.

Consanant with such objects another object of the present invention isto provide such a machine with mechanical means for positively strippingthe. formed articles from the pins at the ejection station which meanscan be lowered to provide operation of the machine without automaticstripping of formed articles at the ejection station.

The invention also furnishes means to adjust the machine for articles ofvarious sizes by providing means to vary the length .and span of strokeof the stripping mechanism.

In a preferred embodiment, the invention comprises stripper fingersprojecting between the parison pins in the ejection station of anautomatic blow molding apparatus; reciprocating means to move thefingers outwardly parallel to the axes of the pins; means to vary thetravel of the fingers; and means to lower the fingers from between thepins to provide operation of the molding apparatus without automaticstripping of the pins.

These and other objects and attendant advantages of the invention willbecome better understood by those skilled in the art by reference to thefollowing detailed description when viewed in light of accompanyingdrawings wherein like components throughout the Figures are indicated bylike numerals and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary plan view of ablow molding apparatus incorporating a stripping device in accordancewith the invention;

FIG. 2 is an enlarged sectional view of the device of FIG. 1 taken alongthe lines 2-2 thereof;

FIG. 3 is a side elevational view of a portion of the stripping deviceof FIG. 1;

FIG. 4 is an end view of the device of FIG. 3;

FIG. Sis an elevational view of a portion of the apparatus of FIG. 1;and

FIG. 6 is a side view of the portion of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENT herein comprises a rotatable andelevatable turret 12 which has three faces spaced apart with sets ofoutwardly extending parison pins 14 on each face. Although the devicedescribed in the cited co-pending application comprises a turret havingdouble the number of faces and operating stations, the functioning ofthe machines are essentially the same for the purposes of thisinvention.

Surrounding the turret 12 are, in counter clockwise order, a preformparison mold station 16, a blow mold station 18 and an ejection stationgenerally indicated at 20.

As is more fully described in the cited co-pending application, the moldstations 16 and 18 include horizontally divide seperable mold halveswhich are separated vertically to allow the pins and molded articlesthereon to clear the cavities in the mold halves when the turret 12 israised as seen in FIG. 2 and rotated by indexing means (not shown). Theturret 12 then can be indexed between stations 14, 16 and 18 in sequenceor in any other order as found suitable. At each indexed point the moldhalves are closed by actuating means (not shown) to define cavitiesabout the ends of the'pins indexed at that station.

With the mold halves closed about the pins 14 at the parisonmold station16, heated plastic material from an injection unit (not shown) isinjected into the cavities thereof to form parisons on the ends of thepins 14.

The mold halves are then opened and the turret 12 is indexed to placethe pins 14 carryingthe parisons at the blow mold station 18 whereuponthe blow mold halves are closed about the parisons which are thenexpanded to assume the form and size of the cavity under air pressuredirected through the parison pins 14.

After separation of the blow mold halves, the turret 12 is indexed againto place the molded articles at the ejection station 20 for stripping aswill be described in greater detail below. After stripping, the cycle isrepeated. The parison pins 14 on the remaining faces of the turret are,of course, indexed at adjacent stations so that for each of the abovedescribed cycles, the other phases of the formation are simultaneouslybeing carried out.

Although a machine operating as described above is preferred, it shouldbe understood that this invention may be incorporated in any blowmolding machine from which plural articles formed on parison pins mustbe stripped.

The ejection station 20 includes a stripper mount 22 (FIG. 2) which isslidably disposed on a pair of supporting bars 24. The bars 24 areinterconnected by a cross member 26 which in turn is connected to a pairof parallel stripper actuating arms 28. As best seen in FIG. 1, the arms28 are interconnected, at their other ends, by a yoke 30. A hydraulicactuator 32, connected to the frame of the machine at oneend and the midportion of the yoke 30 at the other end, longitudinally drives the arms28 to reciprocate the stripper mount 22. 1

Referring now more specifically to FIGS. 3 and 4, a stripper bar 34 isshown disposed on the mount 22 and is provided with plural recesses inthe upper edge to define a series of stripper fingers 36 which extendupwardly between the parison pins 14. A molded article to be stripped,shown in phantom at 38, is disposed on one of the pins 14 for purposesof illustration.

The stripper bar 34 is preferably removably attached to the strippermount 22 so that it may be interchanged to accommodate variousconfigurations of molded articles.

As best seen in FIGS. 1 and 4, a microswitch 40 is disposed on the frameof the machine 10 and is engaged by a threaded stop rod 42 which ismounted to the stripping mount 22 by a threaded collar 44. Themicroswitch is connected to a control system (not shown) for theactuator 32 and serves to, when engaged, provide a limit to movement ofthe stripper mounttoward the machine 10. An adjustment wheel 46 andlockwheel 48, disposed on the rod 42, serve to longitudinally adjust therod so that the point of engagement with the switch 40 can be varied forpurposes t be described below.

The stripper mount 22 is pivotally mounted on pins 50 and 51 to splitclamp ends 52 which encompass the support bars 24 and provide means toadjust the position of the stripper mount 22 along the length of thebars. The pin 50 is provided with a handle'54 on the outer end thereofwhich provides means to lower the stripper fingers to a horizontalposition as shown in phantom in FIG. 3. The support may be held verticalby a detent or other means common in the art.

In FIG. 3, a second microswitch 56 is disposed on the machine 10proximate the other end of the actuating arms 28 and is mounted to beengaged by the yoke 30. Like microswitch 40, the microswitch 56 isconnected to the control system for the actuator 32 and serves to limitthe travel of the stripper mount 22 away from the machine 10.

In operation, and with particular reference to FIGS. 3 and 4, thestripper bar 34 is selected according to the cross sectionalconfiguration of the neck of the article 38 and mounted on the mount 22.The mount 22 is then longitudinally adjusted on the support bars 24 sothat the fingers 36 clear the end of the parison pins 14 when theactuating arms 28 are fully extended against the switch 56. Theadjustment wheel 46 is then turned so that the stop rod 42 actuates theswitch 40 when the fingers 36 are coincident with the neck of thearticle 38 when it is fully in place on the pin 14.

In start up of the machine 10, it is often necessary to make test runsuntil the temperature of the plastic material and other parameters aresuitable. During such start up runs, the molded articles produced aregenerally imperfect and/or non-unifonn and require manual removal fromthe pins. At such times, it is preferable that the automatic strippingstep be bypassed until such test runs are completed. The pivotalmounting of the stripper mount 34 serves to provide means to lower thefingers 36, as described above, for this purpose. With the fingerslowered the machine 10 may be run without the automatic stripping stepuntil the molded article output is satisfactory.

With reference now to FIGS. 5 and 6, means are provided to senseincomplete stripping of the pins 14 or damaged and bent pins. Such meanscomprise feeler fingers 58 mounted in a rocker bar 60 on a bracket 62adjacent the stripper station 20 (FIG. 1). A microswitch 64, connectedto the machine control (not shown) serves to stop the machine operationif the fingers 58 are deflected as shown in FIG. 4.

If an article 38 were to remain on one or more of the pins as seen inphantom in FIG. 5, or if one or more of the pins 14 were to be bentdownwardly, the obstruction would engage the fingers 58 as the turret 12is indexed by the fingers from the ejection station 20 to the parisonmold station 16 thereby stopping the machine until the situation iscorrected.

The fingers 58 are mounted on the bar 60 in selected ones of a series ofspaced vertical holes 66 in the bar. By proper selection of the lengthof the fingers 58 and their lateral position on the bar 60, the feelermechanism can be adjusted to various configurations of molded articles.

What has been set forth above is exemplary to enable those skilled inthe art in the practice of the invention.

What is new and desired to be protected by Letters Patent of the UnitedStates is:

1. In a blow molding apparatus for forming hollow articles including arotatable turret having plural side faces with sets of parison pinsprojecting outwardly therefrom, spaced operating stations including atleast one ejection station disposed therearound and means for indexingsaid turret to place pin sets with formed articles thereon at saidejection station, the improvement comprising mechanical means includingstripper fingers projecting between said pins to engage formed articlesthereon and reciprocating means to move the fingers outwardly parallelto the pins to strip articles formed thereon therefrom, stroke adjustingmeans including stop means adjustable along the path of movement of saidfingers to vary the span of stroke of said fingers, and means to lowersaid fingers from between said pins to bypass the automatic strippingfunction thereof.

2. An apparatus in accordance with claim 1 further including feelermeans adjacent said ejection station to detect the condition of saidpins when said turret is indexed to move said pins from said ejectionstation.

3. In a blow molding apparatus for forming hollow articles including arotatable turret having plural side faces with sets of parison. pinsprojecting outwardly therefrom, spaced operating stations including atleast one ejection station disposed therearound and means for indexingsaid turret to place pin sets with formed articles thereon at saidejection station, the improvement comprising mechanical means includingstripper fingers projecting between said pins to engage formed articlesthereon and reciprocating means to move the fingers outwardly parallelto the pins to strip articles fonned thereon therefrom, stroke adjustingmeans including stop means adjustable along the path of movement of saidfingers to vary the span of stroke of said fingers, and means to lowersaid fingers from between said pins to bypass the automatic strippingfunction thereof, further including feeler means adjacent said ejectionstation to detect the condition of said pins when said turret is indexedto move said pins from said ejection station, wherein said feeler meanscomprises a plurality of upwardly extending fingers disposed on a rockerarm, said fingers being configured to be normally cleared byunincumbered pins when indexed thereby but deflected thereby when saidpins are not cleared or are out of alignment, and switch means tointerrupt operation of said apparatus and disposed to be actuated bysaid rocker arm when said fingers are deflected.

4. An apparatus in accordance with claim 3 wherein said rocker arm isprovided with openings for receiving said feeler fingers at spacedpoints therealong, whereby the position of said feeler fingers alongsaid rocker arm can be altered to correspond to varying molded articleconfigurations.

5. An apparatus in accordance with claim 1 wherein said stop meansinclude first and second microswitches adjacent said reciprocating meansand connected thereto to interrupt operation thereof when actuated, saidfirst switch being disposed adjacent said fingers to limit movement ofsaid reciprocating means toward said apparatus when engaged by saidfingers and actuated, said second switch being disposed to limitmovement of said reciprocating means away from said aparatus when en aed thereb and actuated. p 6. In a blow ioqding appa ratus for forminghollow articles including a rotatable turret having plural side faceswith sets of parison pins projecting outwardly therefrom, spacedoperating stations including at least one ejection station disposedtherearound and means for indexing said turret to place pin sets withformed articles thereon at said ejection station, the improvementcomprising mechanical means including stripper fingers projectingbetween said pins to engage formed articles thereon and reciprocatingmeans to move the fingers outwardly parallel to the pins to striparticles formed thereon therefrom, stroke adjusting means in cludingstop means adjustable along the path of move ment of said fingers tovary the span of stroke of said fingers, and means to lower said fingersfrom between said pins to bypass the automatic stripping functionthereof, said stop means include first and second microswitches adjacentsaid reciprocating means and connected thereto to interrupt operationthereof when actuated, said first switch being disposed adjacent saidfingers to limit movement of said reciprocating means toward saidapparatus when engaged by said fingers and actuated, said second switchbeing disposed to limit movement of said reciprocating means away fromsaid apparatus when engaged thereby and actuated, wherein saidreciprocating means includes at least one support bar disposed parallelto said pins and said stroke adjusting means includes a stripper mountadjustably disposed on said support bar, said mount supporting saidfingers and having a longitudinally adjustable stop rod associatedtherewith parallel to said pins and positioned to engage said firstmicroswitch, whereby adjustment of the position of said mount on saidsupport bar to clear the free ends of said pins with said reciprocatingmeans extended fully away from said machine and adjustment of said stoprod to actuate said first microswitch when said fingers are coincidentwith the other ends of said pins with said reciprocating means disposedtoward said machine provides adjustment of the span of stroke of saidfingers.

7. An apparatus in accordance with claim 1 wherein said means to lowersaid fingers includes a pivotal mount supporting said fingers forpivoting thereof on an axis perpendicular to and in the common plane ofsaid fingers.

8. A mechanism in accordance with claim 1 wherein said reciprocatingmeans and said stroke adjusting means include at least one support bardisposed parallel to said pins and a stripper mount adjustably disposedon said bar, said mount supporting said fingers and having alongitudinally adjustable stop rod associated therewith parallel to saidpins, first and second microswitches associated with said reciprocatingmeans to limit movement thereof toward and away from said one end ofsaid pins respectively, said first microswitch being disposed to beengaged by said stop rod for actuation thereby.

1. In a blow molding apparatus for forming hollow articles including arotatable turret having plural side faces with sets of parison pinsprojecting outwardly therefrom, spaced operating stations including atleast one ejection station disposed therearound and means for indexingsaid turret to place pin sets with formed articles thereon at saidejection station, the improvement comprising mechanical means includingstripper fingers projecting between said pins to engage formed articlesthereon and reciprocating means to move the fingers outwardly parallelto the pins to strip articles formed thereon therefrom, stroke adjustingmeans including stop means adjustable along the path of movement of saidfingers to vary the span of stroke of said fingers, and means to lowersaid fingers from between said pins to bypass the automatic strippingfunction thereof.
 2. An apparatus in accordance with claim 1 furtherincluding feeler means adjacent said ejection station to detect thecondition of said pins when said turret is indexed to move said pinsfrom said ejection station.
 3. In a blow molding apparatus for forminghollow articles including a rotatable turret having plural side faceswith sets of parison pins projecting outwardly therefrom, spacedoperating stations including at least one ejection station disposedtherearound and means for indexing said turret to place pin sets withformed articles thereon at said ejection station, the improvementcomprising mechanical means including stripper fingers projectingbetween said pins to engage formed articles thereon and reciprocatingmeans to move the fingers outwardly parallel to the pins to striparticles formed thereon therefrom, stroke adjusting means including stopmeans adjustable along the pAth of movement of said fingers to vary thespan of stroke of said fingers, and means to lower said fingers frombetween said pins to bypass the automatic stripping function thereof,further including feeler means adjacent said ejection station to detectthe condition of said pins when said turret is indexed to move said pinsfrom said ejection station, wherein said feeler means comprises aplurality of upwardly extending fingers disposed on a rocker arm, saidfingers being configured to be normally cleared by unincumbered pinswhen indexed thereby but deflected thereby when said pins are notcleared or are out of alignment, and switch means to interrupt operationof said apparatus and disposed to be actuated by said rocker arm whensaid fingers are deflected.
 4. An apparatus in accordance with claim 3wherein said rocker arm is provided with openings for receiving saidfeeler fingers at spaced points therealong, whereby the position of saidfeeler fingers along said rocker arm can be altered to correspond tovarying molded article configurations.
 5. An apparatus in accordancewith claim 1 wherein said stop means include first and secondmicroswitches adjacent said reciprocating means and connected thereto tointerrupt operation thereof when actuated, said first switch beingdisposed adjacent said fingers to limit movement of said reciprocatingmeans toward said apparatus when engaged by said fingers and actuated,said second switch being disposed to limit movement of saidreciprocating means away from said apparatus when engaged thereby andactuated.
 6. In a blow molding apparatus for forming hollow articlesincluding a rotatable turret having plural side faces with sets ofparison pins projecting outwardly therefrom, spaced operating stationsincluding at least one ejection station disposed therearound and meansfor indexing said turret to place pin sets with formed articles thereonat said ejection station, the improvement comprising mechanical meansincluding stripper fingers projecting between said pins to engage formedarticles thereon and reciprocating means to move the fingers outwardlyparallel to the pins to strip articles formed thereon therefrom, strokeadjusting means including stop means adjustable along the path ofmovement of said fingers to vary the span of stroke of said fingers, andmeans to lower said fingers from between said pins to bypass theautomatic stripping function thereof, said stop means include first andsecond microswitches adjacent said reciprocating means and connectedthereto to interrupt operation thereof when actuated, said first switchbeing disposed adjacent said fingers to limit movement of saidreciprocating means toward said apparatus when engaged by said fingersand actuated, said second switch being disposed to limit movement ofsaid reciprocating means away from said apparatus when engaged therebyand actuated, wherein said reciprocating means includes at least onesupport bar disposed parallel to said pins and said stroke adjustingmeans includes a stripper mount adjustably disposed on said support bar,said mount supporting said fingers and having a longitudinallyadjustable stop rod associated therewith parallel to said pins andpositioned to engage said first microswitch, whereby adjustment of theposition of said mount on said support bar to clear the free ends ofsaid pins with said reciprocating means extended fully away from saidmachine and adjustment of said stop rod to actuate said firstmicroswitch when said fingers are coincident with the other ends of saidpins with said reciprocating means disposed toward said machine providesadjustment of the span of stroke of said fingers.
 7. An apparatus inaccordance with claim 1 wherein said means to lower said fingersincludes a pivotal mount supporting said fingers for pivoting thereof onan axis perpendicular to and in the common plane of said fingers.
 8. Amechanism in accordance with claim 1 wherein said reciprocating meansand said stroke adjusting means include at leaSt one support bardisposed parallel to said pins and a stripper mount adjustably disposedon said bar, said mount supporting said fingers and having alongitudinally adjustable stop rod associated therewith parallel to saidpins, first and second microswitches associated with said reciprocatingmeans to limit movement thereof toward and away from said one end ofsaid pins respectively, said first microswitch being disposed to beengaged by said stop rod for actuation thereby.